Re: [syzbot] [bluetooth?] general protection fault in l2cap_sock_recv_cb

Edward Adam Davis
2024-06-21T14:18:19Z

please test null ptr defref in l2cap_sock_recv_cb

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git cc8ed4d0a848

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 6db60946c627..b72f5db97ccb 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1239,6 +1239,7 @@ static void l2cap_sock_kill(struct sock *sk)

BT_DBG("sk %p state %s", sk, state_to_string(sk->sk_state));

+ l2cap_pi(sk)->chan->data = NULL;
/* Kill poor orphan */

l2cap_chan_put(l2cap_pi(sk)->chan);
@@ -1481,10 +1482,15 @@ static struct l2cap_chan *l2cap_sock_new_connection_cb(struct l2cap_chan *chan)

static int l2cap_sock_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
{
- struct sock *sk = chan->data;
- struct l2cap_pinfo *pi = l2cap_pi(sk);
+ struct sock *sk;
+ struct l2cap_pinfo *pi;
int err;

+ sk = chan->data;
+ if (!sk)
+ return -ENXIO;
+
+ pi = l2cap_pi(sk);
lock_sock(sk);

if (chan->mode == L2CAP_MODE_ERTM && !list_empty(&pi->rx_busy)) {